i40e: refactor tail_bump check

This patch refactors tail bump check.

Change-ID: Ide0e19171d67d90cb2b06b8dcd4fa791ae120160
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -2840,10 +2840,9 @@ static inline void i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 						  I40E_TXD_QW1_CMD_SHIFT);
 
 	/* notify HW of packet */
-	if (!tail_bump)
+	if (!tail_bump) {
 		prefetchw(tx_desc + 1);
-
-	if (tail_bump) {
+	} else {
 		/* Force memory writes to complete before letting h/w
 		 * know there are new descriptors to fetch.  (Only
 		 * applicable for weak-ordered memory model archs,
@@ -2852,7 +2851,6 @@ static inline void i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 		wmb();
 		writel(i, tx_ring->tail);
 	}
-
 	return;
 
 dma_error:

drivers/net/ethernet/intel/i40evf/i40e_txrx.c

@@ -2068,10 +2068,9 @@ static inline void i40evf_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 						  I40E_TXD_QW1_CMD_SHIFT);
 
 	/* notify HW of packet */
-	if (!tail_bump)
+	if (!tail_bump) {
 		prefetchw(tx_desc + 1);
-
-	if (tail_bump) {
+	} else {
 		/* Force memory writes to complete before letting h/w
 		 * know there are new descriptors to fetch.  (Only
 		 * applicable for weak-ordered memory model archs,
@@ -2080,7 +2079,6 @@ static inline void i40evf_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
 		wmb();
 		writel(i, tx_ring->tail);
 	}
-
 	return;
 
 dma_error: